I've done it every way possible, and I finally ended up with every channel on identical amp systems. Different manufacturers and even different amps in the same line respond to pre outs differently, and cause shifts in balance at various volumes, making your (read it did mine to me) HT seem to come in and out of balance at different volume levels (both on the pre/pro and from the movie). I would strongly recomend even using the 2 channel amp for the fronts (L/R) and the three for the center and rears.
Just my 0.02.
Just my 0.02.